1. Field of the Invention
The present invention relates to a heddle frame for a loom, and to a loom fitted with at least one such frame.
2. Description of the Related Art
In the field of weaving, it is known to use a heddle frame in which the top and bottom cross-rails are mounted on uprights that are parallel to the travel direction of the frame. Each cross-rail is fitted with a bar on which the ends of the heddles carried by the frame are threaded or hooked. The heddles must be capable of moving parallel to the longitudinal direction of the cross-rails in order to adapt their positions to the positions of the warp threads passing through them. To do this, the heddle-carrying bars must remain parallel and accurately spaced apart relative to each other, in spite of dynamic forces, in particular inertial forces, and in spite of static forces, in particular forces due to the warp threads being under tension, all of which are applied to the frame in operation.
In order to guarantee that the bars and the cross-rails remain spaced apart, it is known to use one or more braces that must be capable of being received in the empty volume between the cross-rails. A first technique consists in placing a rod between the cross-rails, which rod is secured to the facing sides of the cross-rails by strips through which screws pass. When action needs to be taken on such braces, in particular in order to adjust their positions along the cross-rails, the operator must take action on the cross-rails in zones that are difficult of access, thus making the work difficult and tiring, and increasing the risk of damaging the warp threads.
U.S. Pat. No. 5,975,147 teaches using a rod that is threaded at one of its ends and that has a drive head at its opposite end, the rod passing through the top cross-rail of a frame and being screwed into a socket secured to the bottom cross-rail. That rod is necessarily small in section since it must be operated in the space occupied by the frame, including in the vicinity of the heddle-carrier bars, thus requiring a flat to be formed on the rod, with such a flat weakening the rod. Creating a flat on a heddle-carrier bar requires the rod to have a particular angular orientation, which means that it is not necessarily screwed by an amount that matches the intended spacing between the cross-rails. Finally, the device for fastening the rod to the bottom cross-rail requires access on the heddle side, thus leading to the same tiring nature and risk of damaging the warp threads as in the above-mentioned device.
U.S. Pat. No. 4,924,916 teaches using a rod of small section, that is threaded at one of its ends and that carries a strip in the form of a rectangular parallelepiped at its other end. It is not possible to adjust the position of the threaded rod parallel to the longitudinal direction of the cross-rails. In addition, while the loom is in operation, opposing deformations of the cross-rails can lead to slack between the thread of the rod and the tapping in the strip, running the risk of inducing contact rust at that level.